1. Field of the Invention
The present invention relates to an image forming apparatus, a developing device that is used in the image forming apparatus, and a process cartridge in which the developing device is integrated to an image carrying member.
Here, image forming apparatuses are, for example, apparatuses that form an image on a recording medium using an electrophotographic image forming system, and include an electrophotographic copying machine, an electrophotographic printer (such as a laser beam printer and an LED printer), and a word processor.
2. Description of the Related Art
Hitherto, in an image forming apparatus using an electrophotographic image forming process, a developing device is used as a device for developing a latent image on a photosensitive drum (image carrying member) using developer.
In this type of developing device, an interval ensuring member is provided at an end portion of a developing roller (developer carrying member) for regulating an interval between the photosensitive drum and the developing roller to a certain interval.
The interval ensuring member is interposed between the photosensitive drum and the developing roller by urging force of a spring or the like, and regulates the interval between the photosensitive drum and the developing roller to a certain interval on the basis of a wall thickness of the interval ensuring member.
The interval ensuring member maintains the distance between the photosensitive drum and the developing roller by contacting the photosensitive drum while rotating along with the developing roller in a rotation direction of the developing roller (refer to Japanese Patent Laid-Open No. 2000-356939 and Japanese Patent Laid-Open No. 2004-163812).
However, in the aforementioned related arts, the interval ensuring member rotates along a surface of the developer carrying member. Therefore, in a longitudinal direction, the interval ensuring member needs to be disposed outward from a developer sealing section in an axial direction (longitudinal direction) of the developer carrying member. This becomes a problem when performing size reduction in the axial direction (longitudinal direction) of the developer carrying member.
The term “sealing section” refers to a structure that suppresses (regulates) leakage of developer from a gap between an end portion of the developer carrying member and a frame member of the developing device by, for example, contacting the end portion of the developer carrying member (the details thereof are given later using, for example, FIG. 7).